Fix status-bar overlap on scroll, and reposition/elevate the avatar menu

- Every tab now wraps its CustomScrollView in SafeArea(top: true) - the
  pinned sort/filter row was riding up underneath the status bar once
  the floating top bar above it fully collapsed, since that bar's own
  internal SafeArea only reserved the inset while it had some height
  left to put it in. Reserving it outside the scrolling region entirely
  fixes this regardless of the floating header's state. Caught live on
  device and backed by a new regression test.
- The avatar menu now covers the top bar (title included) instead of
  sitting below it - positioned off just the status-bar inset rather
  than the top bar's full height on top of that.
- The avatar menu's card now carries a second, tighter contact shadow
  alongside nooDialogShadow - that shadow alone was essentially
  invisible on a small card over a dark theme's near-black background.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.claude/context/styling.md

@@ -236,7 +236,16 @@ blocks are noted where they matter:
   not a modal flow) - there's no existing anchored-popup primitive here
   (`PopupMenuButton`'s own width doesn't stretch to a full content column),
   so don't reach for `showNooSheet`/`showNooDialog` for something shaped
-  like this. Also added `NooTopBar.androidTitleReplacement`: Android has no
+  like this. It's positioned just past the status bar (`SafeArea`'s own
+  inset, not the top bar's full height on top of that) so it covers the
+  top bar - including the tab title - rather than sitting below it, and
+  its card carries two stacked `boxShadow`s rather than just
+  `nooDialogShadow` alone: that one shadow's blur is wide and soft enough
+  to read as basically invisible on a small card over a dark theme's
+  near-black `bg` (a dark, diffuse shadow needs real density close to the
+  edge to be visible against an already-dark backdrop), so a second,
+  tighter, more opaque contact shadow underneath it gives real elevation
+  in both themes. Also added `NooTopBar.androidTitleReplacement`: Android has no
   large title to put a second search row under the way iOS's `search:`
   slot does, so an inline search bar (`AppTopBar` passes a plain
   `ShellSearchLauncher()` when search isn't in the bottom bar) replaces the